Weigh costs, field conditions in making corn seed population decisions

What's the right corn seed population for your farm? Research and field testing shows a range of performance for different seed populations under different conditions.

Seed populations have historically been on the rise in the last few years. Mark Dempsey of Fowler, Illinois, says his dad was planting 24,000 seeds per acre a couple of decades ago. Then, he "saw the benefits of going to 30,000" and made the jump to that level. Dempsey, a National Corn Growers Association yield contest winner, is a firm believer of staying close to the top end of the seed population spectrum, and his corn yields show that's paid off.

"This year, on my winning field, I planted 41,000 [seeds per acre]. That's about as far as I can go on 30-inch rows," he says. "I've planted higher and it doesn't work."

Dempsey's seeding rates are on the high side -- higher than what's optimal for most farmers, according to Pioneer Hi Bred International, Inc., research. In a recent Pioneer study, using $4 per bushel for the final corn price and a seed cost of $170 per bag (or per 80,000 kernels), analysis shows an optimal seeding rate of between 33,000 and 34,000 seeds per acre. According to the research, net income per acre ranges from just under $630 per acre at an 18,000-seed-per-acre rate to around $700 per acre at 42,000 seeds per acre with the arc peaking around $730 per acre at just over 33,000 seeds per acre.

"[Farmers] already know that 40,000 is way too high for non-irrigated production. They're likely trying to decide between planting 33,000 and 34,000 seeds per acre," says Pioneer agronomy information manager Steve Butzen. "If we include the relevant economic parameters of seed cost and grain price, we can arrive at an optimal economic planting rate.

"If farmers planted 30,000 seeds per acre instead of 33,000, it would cost them over $5 per acre. That could easily add up to $5,000 to $10,000 for corn growers who have 1,000 to 2,000 corn acres," Butzen adds.

What's the right corn seed population for your farm? Research and field testing shows a range of performance for different seed populations under different conditions.

Still, some research shows a lower seeding rate, under some conditions, can yield the best results. In a recent study, Ohio State University (OSU) Extension educator and assistant professor Andy Kleinschmidt and OSU Extension researcher Gary Prill found that less is actually better; a "head-to-head comparison" between 30,000-seed and 40,000-seed-per-acre field trials showed the former consistently outyielded the latter. WIth 30,000 seeds-per-acre, yields ended up 12 and 17 bushels per acre higher than 40,000-seed plantings with equal amounts of foliar fungicide applied and 180 and 240 pounds of nitrogen added, respectively.